Second, as METTL3 is a kind of methyltransferase that catalyzes the methyl group to the nucleotide of RNA, especially mRNA, we decided to determine whether ADAR1 could affect methylation of mRNAs by using the m6A dot blot assay in breast cancer cell lines, as shown in Figure 2i–k. Here, METTL3 is linked to breast carcinoma.